Field crops are bred through techniques that take advantage of the plant's method of pollination. A plant is self-pollinating if pollen from one flower is transferred to the same or another flower of the same plant. A plant is cross-pollinated if the pollen comes from a flower on a different plant. A plant is sib-pollinated if pollen from one flower is transferred to another flower of a related plant.
The F.sub.1 hybrid seed of cucumber plants (Cucumis sativus)are produced through a seed parent and a pollen parent. In current cucumber breeding techniques, the seed parent is a gyneocious line, i.e., having only female flowers. The pollen parent is a monoecious line, i.e., having both male and female flowers. For some cucumber hybrids, the pollen plant may be andromonoecious, i.e., having both male and bisexual flowers, or hermaphroditic, i.e., having bisexual flowers.
The female seed parent must be cross-pollinated in order to produce fruits and the F.sub.1 hybrid seeds. However, the pollen parent is capable of self- and sib-pollination, resulting in commercially useless fruits and seeds.
In order to isolate the F.sub.1 hybrid of the female seed parent from the pollen parent fruit, the F.sub.1 hybrid production fields are planted in separate rows: several seed-parent rows alternate with one or two pollen-parent rows. Pollination occurs from insects, mostly bees, carrying pollen from the pollen-parent to the female seed-parent plants, causing cross-pollination which results in F.sub.1 hybrid-seeds. In addition, self-pollination and sib-pollination of the pollen-parent takes place. The mature production field is ultimately composed of rows with F.sub.1 hybrid fruits on the seed-parent plants and rows with pollen-parent fruits. Only the F.sub.1 hybrid fruits have commercial value as F.sub.1 hybrid-seeds. The fruits of the pollen-parent have no commercial value and must be cleared from the hybrid seed production field before the harvest of the fruits of the seed-parent.
This current hybrid seed production method has two distinct disadvantages. First, one-third to one-fifth of the production field is used for planting of pollen-parent plants which bear useless fruits, thus reducing the efficiency of utilization of the field area. Second, the yield of the F.sub.1 hybrid seed production is reduced because of inefficient insect pollination, which requires pollen transfer between plant rows, rather than within plant rows. Thus, it would be desirable to have an efficient F.sub.1 hybrid cucumber seed production method which would overcome these drawbacks.